A catalyst changes the highest point of a reaction profile from 170 kJ to 115 kJ. Reactants remain at 40 kJ and products at 15 kJ.
.1
Calculate the catalysed activation energy.
[2 marks]
.2
Evaluate the statement: "The catalyst releases an extra 55 kJ, so the reaction becomes more exothermic."
[2 marks]
6 marksHigherRequired practical 085.4.2.2 Neutralisation of acids and salt production5.4.2.3 Soluble salts
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.2.2
Spec 5.4.2.3
Original practice question
Answer and supported method checks
Dilute hydrochloric acid is added to excess copper oxide. The black oxide becomes a blue-green copper chloride solution, with black solid remaining.
.1
Write the balanced equation.
[2 marks]
.2
Explain why excess copper oxide is used and how it is removed.
[2 marks]
.3
Explain why the mass of wet crystals would overestimate the mass of salt recovered.
[2 marks]
5 marksFoundation and Higher5.1.2.6 Group 75.1.2.5 Group 1
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.1.2.6
Spec 5.1.2.5
Original practice question
Answer and supported method checks
Chlorine atoms have electron arrangement 2,8,7. Iodine atoms have more occupied electron shells but also seven outer electrons.
.1
Explain why chlorine is more reactive than iodine.
[3 marks]
.2
Compare this trend with the reactivity trend down group 1.
[2 marks]
6 marksHigher5.3.2.1 Moles
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.3.2.1
Original practice question
Answer and supported method checks
Two separate samples each have mass 8.0 g. One is oxygen gas, O2, and the other is sulfur dioxide, SO2.Ar: O = 16, S = 32.
.1
Calculate the amount of oxygen molecules in the oxygen sample.
[2 marks]
.2
Calculate the amount of sulfur dioxide molecules in its sample.
[2 marks]
.3
Explain which sample contains more molecules and by what factor.
[2 marks]
6 marksFoundation and Higher5.4.3.3 Using electrolysis to extract metals
AQA Trilogy 8464
Spec and skills
Paper scope: C1
Spec 5.4.3.3
Original practice question
Answer and supported method checks
A factory uses electrolysis to extract aluminium. One operating mixture needs 1200 energy units per batch; adding cryolite reduces the requirement to 900 units per equal batch.
.1
Calculate the percentage reduction in energy use.
[3 marks]
.2
Explain how cryolite reduces energy use and why the positive electrodes need replacement.
